ASTM C1314-00a
(Test Method)Standard Test Method for Compressive Strength of Masonry Prisms
Standard Test Method for Compressive Strength of Masonry Prisms
SCOPE
1.1 This test method covers procedures for masonry prism construction and testing, and procedures for determining the compressive strength of masonry, f'mt', used to determine compliance with the specified compressive strength of masonry, f `m'. When this test method is used for research purposes, the construction and test procedures within serve as a guideline and provide control parameters.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: C 1314 – 00a
Standard Test Method for
Compressive Strength of Masonry Prisms
This standard is issued under the fixed designation C 1314; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope * meets the specified compressive strength.
4.2 If this test method is used as a guideline for performing
1.1 This test method covers procedures for masonry prism
research to determine the effects of various prism construction
construction and testing, and procedures for determining the
or test parameters on the compressive strength of masonry,
compressive strength of masonry, f , used to determine
mt
deviations from this test method shall be permitted, provided
compliance with the specified compressive strength of ma-
they are reported. Such research prisms shall not be used to
sonry, f 8 . When this test method is used for research
m
verify compliance with a specified compressive strength of
purposes, the construction and test procedures within serve as
masonry.
a guideline and provide control parameters.
4.3 The testing laboratory performing this test method shall
1.2 The values stated in inch-pound units are to be regarded
be certified in accordance with Practice C 1093.
as the standard. The values given in parentheses are for
information only.
NOTE 1—Testing should be overseen by an individual who has dem-
1.3 This standard does not purport to address all of the
onstrated sufficient knowledge and ability through written and practical
examination. Such laboratory technician certification programs are avail-
safety concerns, if any, associated with its use. It is the
able through the National Concrete Masonry Association and others.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Masonry Prism Construction
bility of regulatory limitations prior to use.
5.1 Construct prisms of units representative of those used in
2. Referenced Documents the construction. If units have flutes or ribs that project ⁄2 in.
(12.5 mm) or more from the surface of the unit, remove those
2.1 ASTM Standards:
flutes or ribs by saw cutting flush with the surface of the unit
C 67 Test Methods for Sampling and Testing Brick and
at the base of the flute or rib.
Structural Clay Tile
5.2 Construct a set of prisms for each combination of
C 140 Test Methods for Sampling and Testing Concrete
materials and each test age at which the compressive strength
Masonry Units and Related Units
of masonry is to be determined.
C 1093 Practice for Accreditation of Testing Agencies for
5.3 Build each prism in an opened, moisture-tight bag large
Unit Masonry
enough to enclose and seal the completed prism. Construct
3. Terminology prisms on a flat, level base. Construct prisms in a location
where they will remain undisturbed until transported for
3.1 Definitions:
testing.
3.1.1 set—a set consists of at least three prisms constructed
5.4 Construct prisms as shown in Fig. 1 with units laid in
of the same material and tested at the same age.
stack bond in stretcher position. Orient units in the prism as in
3.2 Notations:
the corresponding construction. At the time of prism construc-
3.2.1 f 8 —specified compressive strength of masonry.
m
tion, the surfaces of the units shall be free of moisture. Where
3.2.2 f —compressive strength of masonry.
mt
the corresponding construction is of multi-wythe masonry
3.2.3 h —prism height.
p
having wythes composed of different units or mortar, build
3.2.4 t —least actual lateral dimension of prism.
p
prisms representative of each different wythe and test sepa-
4. Significance and Use
rately.
5.5 The length of masonry prisms may be reduced from that
4.1 This test method provides a means of verifying that
of an individual unit by saw cutting units prior to prism
masonry materials used in construction result in masonry that
construction. Prisms composed of units that contain closed
cells shall have at least one complete cell with one full-width
This test method is under the jurisdiction of ASTM Committee C15 on
cross web on either end (see Fig. 2). Prisms composed of units
Manufactured Masonry Units and is the direct responsibility of Subcommittee
C15.04 on Research.
without closed cells shall have as symmetrical a cross section
Current edition approved Nov. 10, 2000. Published December 2000. Originally
as possible. The minimum length of prisms shall be 4 in. (100
published as C 1314–95. Last previous edition C 1314–00.
2 mm).
Annual Book of ASTM Standards, Vol 04.05.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
C 1314
FIG. 1 Masonry Prism Construction
representative of those used in the construction. Place addi-
tional grout into the prisms as necessary after each consolida-
tion. Screed off excess and finish the grout so that it is level
with the top of the prism and in contact with the units at the
perimeter of the grout space. Grouted prisms shall contain no
reinforcement.
5.9.2 Where the corresponding construction is to be par-
tially grouted, construct two sets of prisms; grout one set solid
as described in 5.9.1 and leave the other set ungrouted.
5.9.3 Where open-end units or prisms containing grout
between similar wythes are to be grouted, use similar masonry
units as forms to confine the grout during placement. Brace
forms to prevent displacement during grouting. Grout as
described in 5.9.1.
5.9.4 Immediately following the grouting operation, reseal
the moisture-tight bag around the prism.
5.10 Keep all prisms from freezing. Do not disturb or move
prisms for the first 48 h after construction and grouting. Keep
prisms in the moisture-tight bags until 48 h prior to testing.
FIG. 2 Reduction of Hollow Units Prior to Prism Construction
5.11 Store an indicating maximum-minimum thermometer
with the sample and record the maximum and minimum
NOTE 2—When using larger masonry units, experience has shown that
temperatures experienced during the initial 48–h period.
reducing the length of these units prior to prism construction makes their
handling and transportation easier. Thus, these reduced length unit prisms
6. Transporting Masonry Prisms
are less likely to be damaged and are more likely to be properly capped
6.1 Prior to transporting prisms, strap or clamp each prism
and tested. Also, the smaller prism will be less likely to be affected by
plate bending effects during testing, as described in Note 4, and will to prevent damage during handling and transportation. Secure
therefore provide a more accurate assessment of the strength of the
prisms to prevent jarring, bouncing, or tipping over during
materials in the masonry prism. For these reasons, the use of reduced
transporting.
length prisms is encouraged.
7. Curing
5.6 Build masonry prisms with full mortar beds (mortar all
webs and face shells of hollow units). Use mortar representa- 7.1 After the initial 48 h of curing, maintain the bagged
tive of that used in the corresponding construction. Use mortar
prisms in an area with a temperature of 75 6 15°F (24 6 8°C).
joint thickness and a method of positioning and aligning units, Two days prior to testing, remove the moisture-tight bags and
that are representative of the corresponding construction. Use
continue storing at a temperature of 75 6 15°F (24 6 8°C).
mortar joints that are cut flush. For prisms to be grouted, Test prisms at an age of 28 days or at the designated test ages.
remove mortar “fins” that protrude into the grout space.
Test a set of prisms at each age. Prism age shall be determined
5.7 Build prisms a minimum of two units high with a from the time of laying units for ungrouted prisms, and from
height-to-thickness ratio, h /t , between 1.3 and 5.0.
the time of grouting for grouted prisms.
p p
5.8 Immediately following the construction of the prism,
8. Preparation for Testing
seal the moisture-tight bag around the prism.
5.9 Grouted Prisms. 8.1 Measuring Prisms—As shown in Fig. 3, measure the
5.9.1 Where the corresponding construction is to be solidly length and width at the edges of the top and bottom faces of the
grouted, solidly grout the prisms not less than 24 h nor more prisms to the nearest 0.05 in. (1.3 mm). Determine the length
than 48 h following the construction of the prisms. Use grout and width by averaging the four measurements of each
representative of that used in the corresponding construction. dimension. Measure the height of the prism at the center of
Before placing grout, remove mortar droppings from the grout each face to the nearest 0.05 in. (1.3 mm). Determine the height
space. Use grout consolidation and reconsolidation procedures by averaging the four measurements.
C 1314
9.1.2 The surfaces of the platen or plate intended for contact
with the specimen shall have a hardness not less than HRC 60
(BHN 620). The surfaces of the platen and plate shall not
depart from plane surfaces by more than 0.001 in. (0.03 mm)
in any 6–in. (150–mm) dimension.
NOTE 3—Annex A1 includes guidance on determining the required
plate thicknesses based on the configurations of the test specimen and the
test machine.
NOTE 4—Research has shown that the thickness of bearing plates has a
significant effect on the tested compressive strength of masonry prisms
when the bearing area of the plate is not sufficient to cover the area of the
specimen. Plate bending results in nonuniform stress distributions that can
influence the failure mechanisms of the tested specimens. The magnitude
of this effect is controlled by the stiffness of the plate, the size of the
specimen tested, and the strength of the specimen. Tested compressive
strengths will typically increase with increased plate thickness and with
reduced distance to the furthest corner of the specimen. Some testing
laboratories have machine size limitations that limit the practicality of
FIG. 3 Prism Measurement Location
eliminating plate bending entirely. Therefore, the plate thickness require-
ments in 9.1 are intended to provide an adequate level of accuracy in the
8.2 Capping Prisms—Smooth irregularities of the prism’s
compression test results so as to conform to the limits of practicality of the
bearing surfaces using a method that will not reduce the
testing laboratory.
integrity of the prism. Cap top and bottom of prisms prior to
9.2 Installing the Prism in The Test Machine—Wipe clean
testing with sulfur-filled capping or with high-strength gypsum
the bearing faces of the platens, the bearing plates, and the test
cement. Sulfur-filled capping material shall be 40 to 60 %
specimen. Place the test specimen on the lower platen or
sulfur by weight; the remainder may be ground fire clay or
bearing plate. Align both centroidal axes of the specimen with
other suitable inert material passing a No. 100 (150 mm) sieve,
the center of thrust of the machine. As the spherically seated
with or without a plasticizer. Spread the capping material over
upper platen or plate is brought to bear on the specimen, rotate
a level surface that is plane within 0.003 in. (0.076 mm) in 16
the movable portion of the upper platen gently by hand so that
in. (406 mm). Bring the surface to be capped into contact with
uniform seating is obtained.
the capping compound; firmly press down the specimen,
9.3 Loading—Apply the load to the prism up to one-half of
holding the prism so that its axis is at right angles to the
the expected total load at any convenient rate. Apply the
capping surfaces, and the capped ends are parallel within one
remaining load at a uniform rate in not less than 1 nor more
degree. A spirit level (for example, bulls eye level, torpedo
than 2 min.
level) or equivalent method shall be used during the capping
9.4 Observations—Describe the mode of failure as fully as
process to comply with these prism alignment criteria. The
average thickness of the cap shall not exceed ⁄8 in. (3 mm). possible or illustrate, or both, crack patterns and spalling on a
sketch or photograph. Note whether failure occurred on one
Age the caps at least 2 h before testing the specimens.
side or one end of the prism prior to failure of the opposing side
9. Procedure
or end of the prism.
9.1 Test Apparatus—The test machine shall have an accu-
racy of plus or minus 1.0 % over the anticipated load range.
10. Calculation
The upper platen shall be a spherically seated, hardened metal
10.1 Calculate test results as follows:
block firmly attached at the center of the upper head of the
10.1.1 Net Cross-Sectional Area—Take the net cross-
machine. The center of the sphere shall lie at the center of the
sectional area of ungrouted prisms as the net cross-sectional
surface held in its spherical seat but shall be free to turn in any
area of masonry units, which are cut as in the prism, deter-
direction, and its perimeter shall have at least ⁄4 in. (6.3 mm)
mined by measurement or from a representative sample of
clearance from the head to accommodate specimens whose
units that are cut as in the prism, in accordance with Test
bearing surfaces are not parallel. The diameter of the upper
Methods C 140 for concrete masonry and with Test Methods
platen (determined in accordance with A1.3) shall be at least 6
C 67 for clay masonry. Determine net cross-sectional area of
in. (150 mm). A hardened metal bearing plate may be used
fully grouted prisms by multiplying the length and width of the
beneath the specimen to minimize wear of the lower platen of
prism (see 8.1).
the machine.
NOTE 5—Net area of concrete masonry units other than 100 % solid
9.1.1 When the bearing area of the upper platen or lower
units is determined by Test Methods C 140. Net area determined by Test
platen is not sufficient to cover the area of the specimen, a
Methods C 140 is usually slightly different from the minimum net
single steel bearing plate with a thickness equal to at least the
cross-sectional area.
distance from the edge of the platen to the most distant corner
10.1.1.1 Consider clay masonry units whose net cross-
of the specimen shall be placed between the platen and the
capped specimen. The length and width of the steel plate shall sectional area is at least 75 % of the gross cross-sectional area
as 100 % solid.
be at least ⁄4 in. (6 mm) greater than the length and width of
the prisms. 10.1.2 Masonry Prism Strength—Calculate each masonry
C 1314
prism strength by dividing eac
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